Logging is a very handy debugging and diagnostic technique used by developers. Use the logging class provided as part of the Android SDK to log important information about your application to LogCat, but make sure you review your application’s logging implementation prior to publication, as logging has performance drawbacks.
Before releasing your application Review your log carefully so it doesn't leak any confidential data.
Logging is very important whenever your application is in testing mode. Logs will provide you current state and scenario of your application on current device. So it's very helpful whenever you will update your application.
Sometimes Google play rejects your application if they found your Logging mechanism violates the rules.